Estimating Renal Function in Morbidly Obese Patients
This paper aims to evaluate, in a clinical context, current creatinine-based formulas commonly used to calculate renal function in morbidly obese patients.
A retrospective analysis was performed of the estimates of renal function of 63 obese or morbidly obese patients undergoing gastric bypass surgery. Each patient’s glomerular filtration rate (GFR) was calculated using five methods, both before and after surgery, and these approximations were then compared.
Prior to surgery, the values offered by the five formulas for the renal function of this population ranged widely, by over a factor of 2. After surgery, the three weight-based GFR estimation methods indicated that a significant change in GFR had occurred, but the two non-weight-based formulas showed no significant change in estimated GFR.
At baseline and after significant weight loss, creatinine-based formulas differ twofold in their estimates of renal function of the morbidly obese. An accurate method for calculating these patients’ renal function is required to improve patient safety with drug dosing as well as to ensure early detection of renal failure.
KeywordsGFR MDRD Weight loss Surgery
Glomerular filtration rate
Modified diet in renal disease
Body mass index
Body surface area
Ideal body weight
Salazar and Corcoran formula
- 4.NICE. Obesity: the prevention, identification, assessment and management of overweight and obesity in adults and children. National Institute for Health and Clinical Excellence; 2006.Google Scholar
- 6.Martin JH, Fay MF, Udy A, Roberts J, Kirkpatrick C, Ungerer J, et al. Pitfalls of using estimations of glomerular filtration rate in an intensive care population. Intern Med J. 2011. Epub 2011/11/16.Google Scholar
- 7.Diamandopoulos A, Goudas P, Arvanitis A. Comparison of estimated creatinine clearance among five formulae (Cockroft–Gault, Jelliffe, Sanaka, simplified 4-variable MDRD and DAF) and the 24 hours-urine-collection creatinine clearance. Hippokratia. 2010;14(2):98–104. Epub 2010/07/03.PubMedGoogle Scholar
- 9.Jesudason DR, Clifton P. Interpreting different measures of glomerular filtration rate in obesity and weight loss: pitfalls for the clinician. Int J Obes (Lond). 2011. Epub 2011/12/21.Google Scholar